Auto merge of rust-lang#73081 - Dylan-DPC:rollup-1aqk215, r=Dylan-DPC

Rollup of 5 pull requests

Successful merges:

 - rust-lang#72810 (validate basic sanity for TerminatorKind)
 - rust-lang#72989 (Revert pr 71840)
 - rust-lang#72993 (Count the beta prerelease number just from master)
 - rust-lang#73057 (Clean up E0644 explanation)
 - rust-lang#73059 (remove outdated comment)

Failed merges:

r? @ghost

src/bootstrap/lib.rs

@@ -963,29 +963,15 @@ impl Build {
             return s;
         }
 
-        let beta = output(
-            Command::new("git").arg("ls-remote").arg("origin").arg("beta").current_dir(&self.src),
-        );
-        let beta = beta.trim().split_whitespace().next().unwrap();
-        let master = output(
-            Command::new("git").arg("ls-remote").arg("origin").arg("master").current_dir(&self.src),
-        );
-        let master = master.trim().split_whitespace().next().unwrap();
-
-        // Figure out where the current beta branch started.
-        let base = output(
-            Command::new("git").arg("merge-base").arg(beta).arg(master).current_dir(&self.src),
-        );
-        let base = base.trim();
-
-        // Next figure out how many merge commits happened since we branched off
-        // beta. That's our beta number!
+        // Figure out how many merge commits happened since we branched off master.
+        // That's our beta number!
+        // (Note that we use a `..` range, not the `...` symmetric difference.)
         let count = output(
             Command::new("git")
                 .arg("rev-list")
                 .arg("--count")
                 .arg("--merges")
-                .arg(format!("{}...HEAD", base))
+                .arg("refs/remotes/origin/master..HEAD")
                 .current_dir(&self.src),
         );
         let n = count.trim().parse().unwrap();

src/librustc_error_codes/error_codes/E0644.md

@@ -1,6 +1,6 @@
 A closure or generator was constructed that references its own type.
 
-Erroneous example:
+Erroneous code example:
 
 ```compile_fail,E0644
 fn fix<F>(f: &F)

src/librustc_middle/ty/sty.rs

@@ -724,10 +724,6 @@ impl<'tcx> Binder<&'tcx List<ExistentialPredicate<'tcx>>> {
 ///
 /// Trait references also appear in object types like `Foo<U>`, but in
 /// that case the `Self` parameter is absent from the substitutions.
-///
-/// Note that a `TraitRef` introduces a level of region binding, to
-/// account for higher-ranked trait bounds like `T: for<'a> Foo<&'a U>`
-/// or higher-ranked object types.
 #[derive(Copy, Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
 #[derive(HashStable, TypeFoldable)]
 pub struct TraitRef<'tcx> {

src/librustc_mir/dataflow/move_paths/builder.rs

@@ -362,18 +362,17 @@ impl<'b, 'a, 'tcx> Gatherer<'b, 'a, 'tcx> {
     fn gather_terminator(&mut self, term: &Terminator<'tcx>) {
         match term.kind {
             TerminatorKind::Goto { target: _ }
-            | TerminatorKind::FalseEdges { .. }
-            | TerminatorKind::FalseUnwind { .. }
-            // In some sense returning moves the return place into the current
-            // call's destination, however, since there are no statements after
-            // this that could possibly access the return place, this doesn't
-            // need recording.
-            | TerminatorKind::Return
             | TerminatorKind::Resume
             | TerminatorKind::Abort
             | TerminatorKind::GeneratorDrop
+            | TerminatorKind::FalseEdges { .. }
+            | TerminatorKind::FalseUnwind { .. }
             | TerminatorKind::Unreachable => {}
 
+            TerminatorKind::Return => {
+                self.gather_move(Place::return_place());
+            }
+
             TerminatorKind::Assert { ref cond, .. } => {
                 self.gather_operand(cond);
             }
@@ -417,7 +416,7 @@ impl<'b, 'a, 'tcx> Gatherer<'b, 'a, 'tcx> {
                 ref operands,
                 options: _,
                 line_spans: _,
-                destination: _
+                destination: _,
             } => {
                 for op in operands {
                     match *op {

src/librustc_mir/interpret/terminator.rs

@@ -50,7 +50,13 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                 self.go_to_block(target_block);
             }
 
-            Call { ref func, ref args, destination, ref cleanup, .. } => {
+            Call {
+                ref func,
+                ref args,
+                destination,
+                ref cleanup,
+                from_hir_call: _from_hir_call,
+            } => {
                 let old_stack = self.frame_idx();
                 let old_loc = self.frame().loc;
                 let func = self.eval_operand(func, None)?;

src/librustc_mir/transform/validate.rs

@@ -3,10 +3,13 @@
 use super::{MirPass, MirSource};
 use rustc_middle::mir::visit::Visitor;
 use rustc_middle::{
-    mir::{Body, Location, Operand, Rvalue, Statement, StatementKind},
-    ty::{ParamEnv, TyCtxt},
+    mir::{
+        BasicBlock, Body, Location, Operand, Rvalue, Statement, StatementKind, Terminator,
+        TerminatorKind,
+    },
+    ty::{self, ParamEnv, TyCtxt},
 };
-use rustc_span::{def_id::DefId, Span, DUMMY_SP};
+use rustc_span::def_id::DefId;
 
 pub struct Validator {
     /// Describes at which point in the pipeline this validation is happening.
@@ -30,27 +33,38 @@ struct TypeChecker<'a, 'tcx> {
 }
 
 impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
-    fn fail(&self, span: Span, msg: impl AsRef<str>) {
+    fn fail(&self, location: Location, msg: impl AsRef<str>) {
+        let span = self.body.source_info(location).span;
         // We use `delay_span_bug` as we might see broken MIR when other errors have already
         // occurred.
         self.tcx.sess.diagnostic().delay_span_bug(
             span,
-            &format!("broken MIR in {:?} ({}): {}", self.def_id, self.when, msg.as_ref()),
+            &format!(
+                "broken MIR in {:?} ({}) at {:?}:\n{}",
+                self.def_id,
+                self.when,
+                location,
+                msg.as_ref()
+            ),
         );
     }
+
+    fn check_bb(&self, location: Location, bb: BasicBlock) {
+        if self.body.basic_blocks().get(bb).is_none() {
+            self.fail(location, format!("encountered jump to invalid basic block {:?}", bb))
+        }
+    }
 }
 
 impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> {
     fn visit_operand(&mut self, operand: &Operand<'tcx>, location: Location) {
         // `Operand::Copy` is only supposed to be used with `Copy` types.
         if let Operand::Copy(place) = operand {
             let ty = place.ty(&self.body.local_decls, self.tcx).ty;
+            let span = self.body.source_info(location).span;
 
-            if !ty.is_copy_modulo_regions(self.tcx, self.param_env, DUMMY_SP) {
-                self.fail(
-                    DUMMY_SP,
-                    format!("`Operand::Copy` with non-`Copy` type {} at {:?}", ty, location),
-                );
+            if !ty.is_copy_modulo_regions(self.tcx, self.param_env, span) {
+                self.fail(location, format!("`Operand::Copy` with non-`Copy` type {}", ty));
             }
         }
 
@@ -65,16 +79,107 @@ impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> {
                 Rvalue::Use(Operand::Copy(src) | Operand::Move(src)) => {
                     if dest == src {
                         self.fail(
-                            DUMMY_SP,
-                            format!(
-                                "encountered `Assign` statement with overlapping memory at {:?}",
-                                location
-                            ),
+                            location,
+                            "encountered `Assign` statement with overlapping memory",
                         );
                     }
                 }
                 _ => {}
             }
         }
     }
+
+    fn visit_terminator(&mut self, terminator: &Terminator<'tcx>, location: Location) {
+        match &terminator.kind {
+            TerminatorKind::Goto { target } => {
+                self.check_bb(location, *target);
+            }
+            TerminatorKind::SwitchInt { targets, values, .. } => {
+                if targets.len() != values.len() + 1 {
+                    self.fail(
+                        location,
+                        format!(
+                            "encountered `SwitchInt` terminator with {} values, but {} targets (should be values+1)",
+                            values.len(),
+                            targets.len(),
+                        ),
+                    );
+                }
+                for target in targets {
+                    self.check_bb(location, *target);
+                }
+            }
+            TerminatorKind::Drop { target, unwind, .. } => {
+                self.check_bb(location, *target);
+                if let Some(unwind) = unwind {
+                    self.check_bb(location, *unwind);
+                }
+            }
+            TerminatorKind::DropAndReplace { target, unwind, .. } => {
+                self.check_bb(location, *target);
+                if let Some(unwind) = unwind {
+                    self.check_bb(location, *unwind);
+                }
+            }
+            TerminatorKind::Call { func, destination, cleanup, .. } => {
+                let func_ty = func.ty(&self.body.local_decls, self.tcx);
+                match func_ty.kind {
+                    ty::FnPtr(..) | ty::FnDef(..) => {}
+                    _ => self.fail(
+                        location,
+                        format!("encountered non-callable type {} in `Call` terminator", func_ty),
+                    ),
+                }
+                if let Some((_, target)) = destination {
+                    self.check_bb(location, *target);
+                }
+                if let Some(cleanup) = cleanup {
+                    self.check_bb(location, *cleanup);
+                }
+            }
+            TerminatorKind::Assert { cond, target, cleanup, .. } => {
+                let cond_ty = cond.ty(&self.body.local_decls, self.tcx);
+                if cond_ty != self.tcx.types.bool {
+                    self.fail(
+                        location,
+                        format!(
+                            "encountered non-boolean condition of type {} in `Assert` terminator",
+                            cond_ty
+                        ),
+                    );
+                }
+                self.check_bb(location, *target);
+                if let Some(cleanup) = cleanup {
+                    self.check_bb(location, *cleanup);
+                }
+            }
+            TerminatorKind::Yield { resume, drop, .. } => {
+                self.check_bb(location, *resume);
+                if let Some(drop) = drop {
+                    self.check_bb(location, *drop);
+                }
+            }
+            TerminatorKind::FalseEdges { real_target, imaginary_target } => {
+                self.check_bb(location, *real_target);
+                self.check_bb(location, *imaginary_target);
+            }
+            TerminatorKind::FalseUnwind { real_target, unwind } => {
+                self.check_bb(location, *real_target);
+                if let Some(unwind) = unwind {
+                    self.check_bb(location, *unwind);
+                }
+            }
+            TerminatorKind::InlineAsm { destination, .. } => {
+                if let Some(destination) = destination {
+                    self.check_bb(location, *destination);
+                }
+            }
+            // Nothing to validate for these.
+            TerminatorKind::Resume
+            | TerminatorKind::Abort
+            | TerminatorKind::Return
+            | TerminatorKind::Unreachable
+            | TerminatorKind::GeneratorDrop => {}
+        }
+    }
 }

src/librustc_mir/util/elaborate_drops.rs

@@ -233,6 +233,8 @@ where
                     .patch_terminator(bb, TerminatorKind::Goto { target: self.succ });
             }
             DropStyle::Static => {
+                let loc = self.terminator_loc(bb);
+                self.elaborator.clear_drop_flag(loc, self.path, DropFlagMode::Deep);
                 self.elaborator.patch().patch_terminator(
                     bb,
                     TerminatorKind::Drop {
@@ -243,7 +245,9 @@ where
                 );
             }
             DropStyle::Conditional => {
-                let drop_bb = self.complete_drop(self.succ, self.unwind);
+                let unwind = self.unwind; // FIXME(#43234)
+                let succ = self.succ;
+                let drop_bb = self.complete_drop(Some(DropFlagMode::Deep), succ, unwind);
                 self.elaborator
                     .patch()
                     .patch_terminator(bb, TerminatorKind::Goto { target: drop_bb });
@@ -315,7 +319,7 @@ where
                 // our own drop flag.
                 path: self.path,
             }
-            .complete_drop(succ, unwind)
+            .complete_drop(None, succ, unwind)
         }
     }
 
@@ -344,7 +348,13 @@ where
         // Clear the "master" drop flag at the end. This is needed
         // because the "master" drop protects the ADT's discriminant,
         // which is invalidated after the ADT is dropped.
-        (self.drop_flag_reset_block(DropFlagMode::Shallow, self.succ, self.unwind), self.unwind)
+        let (succ, unwind) = (self.succ, self.unwind); // FIXME(#43234)
+        (
+            self.drop_flag_reset_block(DropFlagMode::Shallow, succ, unwind),
+            unwind.map(|unwind| {
+                self.drop_flag_reset_block(DropFlagMode::Shallow, unwind, Unwind::InCleanup)
+            }),
+        )
     }
 
     /// Creates a full drop ladder, consisting of 2 connected half-drop-ladders
@@ -878,7 +888,11 @@ where
                     self.open_drop_for_adt(def, substs)
                 }
             }
-            ty::Dynamic(..) => self.complete_drop(self.succ, self.unwind),
+            ty::Dynamic(..) => {
+                let unwind = self.unwind; // FIXME(#43234)
+                let succ = self.succ;
+                self.complete_drop(Some(DropFlagMode::Deep), succ, unwind)
+            }
             ty::Array(ety, size) => {
                 let size = size.try_eval_usize(self.tcx(), self.elaborator.param_env());
                 self.open_drop_for_array(ety, size)
@@ -889,10 +903,20 @@ where
         }
     }
 
-    fn complete_drop(&mut self, succ: BasicBlock, unwind: Unwind) -> BasicBlock {
-        debug!("complete_drop(succ={:?}, unwind={:?})", succ, unwind);
+    fn complete_drop(
+        &mut self,
+        drop_mode: Option<DropFlagMode>,
+        succ: BasicBlock,
+        unwind: Unwind,
+    ) -> BasicBlock {
+        debug!("complete_drop({:?},{:?})", self, drop_mode);
 
         let drop_block = self.drop_block(succ, unwind);
+        let drop_block = if let Some(mode) = drop_mode {
+            self.drop_flag_reset_block(mode, drop_block, unwind)
+        } else {
+            drop_block
+        };
 
         self.drop_flag_test_block(drop_block, succ, unwind)
     }
@@ -907,11 +931,6 @@ where
     ) -> BasicBlock {
         debug!("drop_flag_reset_block({:?},{:?})", self, mode);
 
-        if unwind.is_cleanup() {
-            // The drop flag isn't read again on the unwind path, so don't
-            // bother setting it.
-            return succ;
-        }
         let block = self.new_block(unwind, TerminatorKind::Goto { target: succ });
         let block_start = Location { block, statement_index: 0 };
         self.elaborator.clear_drop_flag(block_start, self.path, mode);
@@ -1028,6 +1047,11 @@ where
         self.elaborator.patch().new_temp(ty, self.source_info.span)
     }
 
+    fn terminator_loc(&mut self, bb: BasicBlock) -> Location {
+        let body = self.elaborator.body();
+        self.elaborator.patch().terminator_loc(body, bb)
+    }
+
     fn constant_usize(&self, val: u16) -> Operand<'tcx> {
         Operand::Constant(box Constant {
             span: self.source_info.span,